Acid-resistant polymers and their production



' Nav. l, 1949 P. H. CARNELL ACID-RESISTANT POLYMERS AND THEIRPRODUCTION Filedvuay 29, 194e HOLSVBH HOlDV-IH HBEQHDS HOLVNOiDVHd s MYL NVENTOR. PAUL H.CARNELL new` 0A AT TORN mnzxomma Patented Nov.v l,1949 ACID-RESISTANT POLYMERS AND THEIR PRODUCTION Paul H. Carnell,Bartlesville, Okla., assigner to vPhillips Petroleum Company, acorporation of Delaware Application May 29, 1946, Serial No. 673,190 sclaims. (ci. 26o-lessi This invention relates to polymers and theirproduction. In one embodiment it relates to the formation of polymers ofallyl chloride suitable as lubricants. Specific features of theinvention involve the formation and use of polymers containing combinedchlorine and uorine which are highly resistant to the action of liquidhydrocarbons and of acids.

In many industrial plants today, strong mineral acids are employed asreactants, treating agents, or catalysts. The serious problemsencountered are so Well known as hardly to require recitation. The' mostimportant, of course, are problems caused by the corrosive nature of theacids, and are overcome only by careful selection of materials ofconstruction and methods of equipment fabrication, and addition ofinhibiting agents to the acids. Numerous valves, pumps, and other itemshaving moving parts are essentials in such a plant set-up. A host ofmaterials have been suggested and tried as lubricants in such acidservice, but without complete success being realized. Lubricants havingproper viscosity and oiliness are subject to chemical attack by theacid,

' while materials which resist attack are decient in one or more of thenecessary qualities of a good lubricant.

Within the last few years, hydrogen fluoride has developed from littlemore than a mere laboratory curiosity into an industrial chemical of thefirst importance. This has been due primarily, though by no meansexclusively, to the recognition of its remarkable catalytic propertiesin a number of organic reactions. The most important commercially atthis time is the use of concentrated hydrogen fluoride, especiallysubstantially anhydrous, to catalyze the reaction of low-boilingisoparaiins, such as isobutane and isopentane, with olens to produceisoparaffmic motor fuels of high antiknock value. The alkylate soproduced was used during the recent War in literally millions of gallons`of aviation fuel as the principal high antiknock fuel componentthereof. In the HF alkylation plants are to be found streams ofconcentrated acid, of liquid hydrocarbons, of dilute aqueous acid, andmixtures of acid and hydrocarbons. The numerous valves and pumps in HFalkylation plants have been lubricated with many different compositionsoffered in the trade for this purpose, and with various compositionsWorked out by the laboratory and plant Workers. None of these, however,has been found fully adequate in eliminating attack by acid and/orsolution in hydrocarbons. and many are so poor as to be hardly worthusing. Similar problems are encountered in other processes usingconcentrated hydrogen iluoride as catalyst or reactant, such asalkylation of phenols with olens, reconstruction of liquid hydrocarbons,formation of alkyl luorides by addition of HF to olefns, and the like.While anhydrous hydrogen chloride is not often used as catalyst, it isfrequently employed as a reactant, and sometimes in liquefied form as asolvent or dehydrating agent. This acid is likewise severe in its actionon greases and other lubricants.

A process involving use of aqueous hydrofluoric acid which has importantcommercial possibilities is the hydration of oleiins to form thecorresponding alcohols, through the action of aqueous hydrogen fluoride.As described in the copending application of F. E. Frey, Serial No.521,833, filed February l0, 1944, now U. S. Patent No. 2,484,702,aqueous HF solutions having an dartid concentration of 40 to 50 per centare generally preferred, and reaction temperature ranges from 0 to 300QC.

While aqueous HF generally does not attack most lubricants as severelyas concentrated or substantially anhydrous acid, it has still beendifficult to find gieases suitable for use in contact with the weakeracid, as one or more components of the grease are dissolved out, or thegrease deteriorates by forming lumps, sticking, or disintegrating. Thesame is true of aqueous solutions of hydrochloric acid, used in manywell known industrial processes.

It is an object of this invention to produce lubricants suitable for usein contact with aqueous or anhydrous mineral acids and/or liquid orgaseous hydrocarbons. Another object is to provide polymers suitable forsuch use. A further object is to polymerize allyl halides. A stillfurther object is to produce ilumine-containing polymers. Yet anotherobject is to subject allyl chloride or its homologs to a dualpolymerizing treatment whereby highly insoluble viscous polymers of alubricating consistency are formed. A further object is to produce avalve grease of satisfactory fluidity for forcing into a valve, butwhich during use in contact with liquid hydrocarbons is increased inviscosity to the degree requisite for satisfactory lubrication over along period of time. Yet another object is to produce a lubricant whichis particularly resistant to anhydrous and concentrated hydrogenfluoride. Other objects and advantages of the invention will beapparent, to one skilled in the art, from the accompanying disclosureand discussion.

While polymers of various organic materials have heretofore beensuggested for use as lubriv the process.

cants, and the properties of such polymers have in some instances beenadequate for given applications, no lubricant of any kind, Whetherpolymeric or otherwise, has been found entirely suitable for uses inwhich contact with acid and hydrocarbons is involved. I. have found,however, that if an allyl halide, preferably allyl chloride, besubjected to the polymerizing steps described below, a polymer isproduced which is very satisfactory for such purposes. First, if aproduct insoluble in hydrocarbons is desired, the allyl chloride istreated with free oxygen and/or other oxidizing agents such, forexample, as nitrogen oxides or organic peroxides to eect what isapparently a preliminary partial polymerization in which at least partof the monomer is converted into polymers. The total treated material,or the polymer content thereof, is next subjected to reaction in thepresence of substantial amounts of concentrated hydrogen fluoride, whichapparently acts both as a polymerization catalyst and as a reactant. Theresulting viscous polymer, which contains both chlorine and fluorine incombined form, is insoluble in hydrocarbons provided the rst step ofoxidative polymerization has been employed, and is insoluble in aqueousacids of moderate strength, but is soluble in concentrated acids, suchas anhydrous hydrogen fluoride. This deficiency is overcome bysubjecting the fluorinecontaining polymer to an additional polymerizingtreatment at elevated temperature, preferably in the absence of added HFor other catalyst or reactant, thereby producing a highly viscous andhighly polymerized final product.

The first step of the process may utilize a suitable oxidizingpolymerization agent, preferably any gas containing free oxygen, such asair, or one or more organic peroxides, such as benzoyl peroxide oracetyl peroxide, or both oxygen and peroxide. Best results appear toresult from the combined use of air and benzoyl peroxide. The amount ofperoxide required may vary from 0.5 per cent by weight of the allylchloride up to 50 per cent or even more, depending on the other reactionconditions. The reaction conditions may vary over a wide range, butmoderate temperatures, such as to 50 C., and moderate pressures, such asatmospheric or near-atmospheric, are preferred. At short reaction timesa relatively large amount of l peroxide and/or air must be used, whereasthe amounts of these agents may be cut down substantially if a longreaction time is economically feasible. The resistance of the ultimatepolymeric material to the action of liquid hydrocarbon solvents, such asgasoline, appears to be dependent upon the severity of this first stepof A mild treatment is insucient to give the insolubility usuallydesired and accordingly the amount of peroxide, air, temperature and/orreaction time must be sufficiently great to result in a final productresistant to the solvent action of liquid hydrocarbons. On the otherhand, a less severe treatment or even no treatment is suitable whereonly resistance to acids is desired of the lubricant product.

Efliuents of the rst step may be treated for recovery of excess peroxideif desired, or they may be passed directly to the second stage.Unreacted allyl chloride may first be separated and recycled to the rststage treatment. Likewise, some of the lower molecular weight polymersmay be distilled off and only the heavier material passed to the secondstage. Concentrated hydrogen fluoride, preferably in substantial excessof that to be consumed, is admixed in the second stage with thepre-treated allyl chloride material. Commercial anhydrous hydrogenfiuorlde is probably the most satisfactory, although any hydrogeniiuoride having a concentration of approximately or 90 per cent orhigher is effective. The second stage reaction may be carried out atelevated temperatures and pressures, but it is preferred to usetemperatures of from 0 to 50 C. and approximately atmospheric pressure.Reaction may be continued for a length of time suilicient to give alubricant of the desired viscosity; the longer the treatment, the moreviscous the product. This control of reaction time enables variousacid-resistant and hydrocarbon-resistant lubricants to be prepared for awide variety of uses. Elevated temperatures likewise tend to produce amore viscous product.

Hydrogen fluoride acts as a polymerization catalyst in the second stage,and in addition a substantial amount of hydrogen fluoride enters intochemical combination to give a product containing combined fiuorine aswell as combined chlorine. Hydrogen chloride is liberated by thereaction so that the product contains less chlorine than would be thecase if it were a simple polymer of allyl chloride. The hydrogenchloride may advantageously be withdrawn from thc reaction as formed.Eluents from the second stage reaction are treated to remove any excesshydrogen fluoride, hydrogen chloride, and unpolymerized allyl chloride.This is readily accomplished by a simple heating and/or reduction inpressure. The lower boiling components of the polymer may likewise beremoved by distillation. In the event the preliminary oxidativepolymerization step described above is not used, the second stage justdiscussed becomes the first stage of the process.

The final step in the present process, which serves to make the polymerresistant to the action of concentrated hydrogen fluoride or otherconcentrated acids, is accomplished by heating the product of the HFpolymerization at an elevated temperature for a substantial period oftime. Ordinarily only the polymer is given this treatment, though thetotal effluents of the HF polymerization step, or the total effluentsminus HC1 and/ or HF, may likewise be so treated. A temperature higherthan that used in the earlier stages of the process is ordinarilyemployed, preferably atleast C. The temperature chosen will depend onthe desired viscosity and degree of acid resistance of the nal product,but is usually in the range of` 100 to 300 C. The reaction time may varyfrom a few minutes at the higher temperatures to one or more hours atthe lower temperatures within the given range. Hydrogen fluoride fromthe preceding stage or freshly-added hydrogen fluoride or otherpolymerization catalyst may be present, though this is not necessary andhence is seldom preferred.

The accompanying drawing represents in dlagrammatic form one arrangementof apparatus elements and flow of material therethrough suitable for thepractice of my invention. No attempt has been made to show all theldetails of auxiliary equipment such as valves, heating and coolingmeans, pumps, control elements or the like as these may readily besupplied by one skilled in the art. `It will be obvious that variousmodifications. nay be made Without departing from the invenion.

In the drawing, allyl chloride is introduced via line 2 into reactor 4.An organic peroxide, such as benzoyl peroxide, may be introduced fromline 6, while air or other oxygen-containing gas may be introduced fromline 8. This gas may, if desired, be allowed to bubble up through theliquid reaction mixture in reactor 4, and line l is provided forcontinuous or intermittent withdrawal of excess air. Suitable means forvigorously agitating the reaction mixture are provided; in someinstances the passage of air will be sufficient to accomplish this.Reactor 4 may be operated continuously or by batches. The partiallypolymerized material is withdrawn through line I2 and may be passed vialine i4 into fractionator I6, which is provided with bubble caps orpacking, or which may be a simple flash chamber. Part or all of theunreacted allyl chloride is withdrawn overhead through line i8 andrecycled via lines and 2 to reactor 4. Likewise, the polytherein. Theexcess HF is withdrawn from fractionator 56 via line 62 for recycle tothe reactor 48. Any HC1 present in the liquid reactor eliluents is takenoff as an overhead product of fractionator 56 through line 64. The HC1produced in this process may be utilized as a starting material in themanufacture of allyl chloride by any of the known methods, so that noneof the chlorine content of the allyl chloride is wasted. There may stillbe a substantial amount of unpolymerized allyl chloride present afterthe second stage reaction and this may be separated in fractionator 56and returned via lines 66 and 20 to the rst reactor 4.

The total ilumine-containing polymer may be withdrawn through line 60and passed to reactor 12, which is equipped with heater 14 for effectmermay be topped so that some of the lower boiling polymer components arewithdrawn, as through line 22, and the heavier unvaporized material iswithdrawn from unit I6 through line 24. If any low boiling polymericmaterial is separated at this point, it may be recycled to reactor 4 vialines 22 and 26.

If a substantial amount of benzoyl peroxide or other peroxide stillremains in uncombined form, it may be recovered in any suitable mannerin unit 28, By the method shown in the drawing, total efliuent ofreactor 4 from line l2, or the bottom product of fractionator I8 fromline 24, is passed via lines 38 and 32 into the top of unit 26 which ispacked with suitable material for encouraging liquid-liquid contact.Into the bottom of scrubber 28 is introduced ethanol from line 34, Theethanol passes countercurrently to the allyl chloride material inscrubber 28 and extracts benzoyl peroxide therefrom. The rich ethanolsolvent is withdrawn through line 36 and passes into evaporator 38 inwhich the ethanol is separated from the benzoyl peroxide. The former isreturned via line 40 for reuse in scrubber 28, while the peroxide ispassed through lines 42 and 6 to reactor 4. Peroxide-free material isrecovered from scrubber 28 by way of line 44.

The thus-pretreated allyl chloride which has been partially polymerizedis passed from line or line 44 via line 46 into the second stage reactor48, wherein it is admixed with concentrated hydrogen fluoride enteringfrom line 50. If the oxidative polymerization just described is notcarried out, the allyl chloride feed to the process is introduced intoreactor 48 (which under such circumstances is the first stage reactor)through lines 49 and 46. Stirring or other agitating means (not shown)are preferably provided within reactor 48. The reaction is allowed toproceed until a product of desired viscosity is obtained. Liberatedhydrogen chloride may be withdrawn continuously or intermittentlythrough line 52. Hydrogen fluoride carried by this gaseous stream may berefluxed back into reactor 48 by means not shown, or the mixture of HC1and HF may be passed through line 54 into fractionator 56 for separationof the two hydrogen halides, one from the other. The total reactionmixture is withdrawn from reactor 48 via line 58 and may be passed intofractionator 56. In this unit, which may be constructed in any suitablemanner known to the art, any remaining hydrogen iiuoride and hydrogenchloride are separated overhead from the viscous polymer which isrecovered through line 60. It may be mentioned here that a substantialexcess of hydrogen uoride is preferably used in reactor 48 over thequantity required to act as catalyst and reactant ing thermalpolymerization. Some of the light fractions of the polymer infractionator 56 may be separated oi and withdrawn through line 68, orreturned through lines 18 and 46 to the reactor 48, and only the heavierfractions subjected to thermal polymerization in reactor 12; or part ofthe lighter polymer fractions may also be passed to reactor 12 via line16. If hydrogen fluoride is to be used in reactor 12, it may be obtainedfrom line 62 via line 80. Although usually not preferred, the totalreaction products from reactor 48 may by-pass fractionation 56 and god1- rectly to thermal polymerizer 12 by way of lines 18 and 60. Thepolymerization reactor 12 may be of a continuous type, such as a tubestill, or may be a drum-type reactor operated either intermittently bybatches or continuously. Light materials liberated during the heatingperiod, such as HC1, HF, allyl chloride, and low polymers, are withdrawnthrough line 82. The final viscous acid-resistant lubricating polymer isrecovered through line B4.

The following data are presented in order to illustrate some of thepreferred methods of preparing lubricants in accordance with theinvention, and to show certain properties of polymers produced undervarying reaction conditions. It will be obvious that these examples arenot exhaustive of the broad scope of the invention.

Eample I A sample of fresh allyl chloride was placed in a Monel beakerand an approximately equal volume of commercial anhydrous hydrouoricacid was added to the halide. The reaction proceeded rapidly at roomtemperature. The reactants were allowed to stand for several hours whilethe acid evaporated olf. The mixture was then heated to about C. toremove hydrouoric acid, hydrogen chloride, and unreacted allyl chloride.The product was a viscous oil. 'I'his polymer was appreciably soluble inisooctane, and concentrated hydrofluoric acid dissolved in it readily.

Example II A sample of allyl chloride which had been standing exposed toair for several months was polymerized. This material had a substantialperoxide content. Into a 50o-ml. Monel beaker at room temperature wereplaced g. of the allyl chloride and 150 g. of commercial anhydrous HE'.Reaction began immediately and appeared to proceed more rapidly when themixture was stirred. The reaction mixture was allowed to stand for aboutone hour at room temperature while HF boiled off. The reaction appearedto have ceased then, and the beaker was heated to 76 about 100 C. on ahot plate to remove HF. HC1.

- an hour at 150 to 200 C., producing an extremeand unreacted allylchloride. Polymer yield was about 50%.' The product, which 'was a blackviscous oil, was tested for solubility at room temperature in variousliquids as follows:

A portion of this polymer was heated for about ly viscous grease-likeproduct.

Samples of polymer heated at 150 to 200 C'. and polymer not heated at150 to 200 C. were tested at room temperature as follows:

8 chloride, benzene hexachloride, benzene hexabromide,hexachlorobenzene, and the like, which add body and increase theviscosity of the lubricant mixture. These halogenated materials are alsofairly resistant. to solution in hydrocarbons.

When certain types of valves are to be lubricated with viscous allylhalide polymers, dilculty is encountered in obtaining as completelubrication as is desired because of the failure of the lubricant to owsuillciently to ll the lubricating grooves in the valve. Once theviscous polymer is forced into place, however, it loses a certain amountof its tackiness and has a greater lubricity apparently because of thesolution of a l5 small amount of HF in the lubricant.

A particularly eiective method of lubricating such valves or othersurfaces with the more viscous and tacky polymers of this invention isto admix same with a material which imparts greater Contact MaterielTested Testing Agent (EmeSS) gime. Appearance at End of Contact Timeoui-s Polymer heated at 150 to 200 C Isooctaue 24 Polymer unchanged;isooctane very slightly colored.

Polymer not heated at 150 to 200 C... ..-..do 24 D0 Polymer heated at150 to 200 C Commercial anhydrous HF, l Polymer unchanged; HF paleyellow. Polymer not heated at 150 to 200 0.-. ..do 1 Polymer more fluid;HF dark brown Example III Testing Agent cfffgltlct Appearance at'End ofContact (Excess) hours Time Isooctane Polymer unchanged; isooctane clearand colorless. Commercial anliy- 15 Polymer more Huid; HF color indrousHF. disates very small amount of so ution.

As pointed out hereinabove, the total allyl chloride which has beensubjected to oxidative polymerization with free oxygen, peroxides, orother oxidation agents, or a heavy fraction of the thustreated material,may be polymerized with hydrogen fluoride, and all or a fraction of theproduct may be subsequently heated to produce an acid- Y resistantlubricant. Various fillers and additives may be mixed with the lubricantto produce a material having the desired consistency for a givenapplication. Thus graphite, being insoluble in both hydrocarbons andacids, as well as having lubricant properties of its own, is eminentlysuitable for incorporation into an HF-allyl chloride polymer lubricantcomposition intended for use in plug'valves in acid-hydrocarbon service.The amount of graphite or other additive used is of course dependent onthe viscosity of the polymer and the desired viscosity of the product.In lubricants to be used in contact with acids there may be incorporatedhighly halogenated organic compounds, such as naphthalene tetra- 30lubricity, which preferably does not react with the polymers, whichpreferably does not react with the fluids which are to come into contactwith the grease, such as acids, alcohols or hydrocarbons, but which issoluble in such fluids. Although other materials may be used,chlorinated organic liquids or oils are preferred. Examples are:chlorinated parafiin wax, hexachlorobutadiene, lauryl chloride,hexachloropropylene, tetrachloroethylene, etc. The amount of chlorinatedorganic liquid or oil added to the polymer may vary considerably and isdependent on the viscosity of the chlorinated organic oil or liquidadded, the viscosity of the polymer, and the desired application of thelubricant.

Addition of these materials to the thermally polymerized HF-allylchloride polymer produces lubricants of somewhat decreased viscosity andgreater lubricity. Since these lubricants ilow relatively easily, theyare more readily charged to the system and, for particular applications,such as the lubrication of plug valves in HF alkylation units, are moreefficient in reaching all parts of the valve requiring lubrication. Thechlorinated organic liquid or oil added to the allyl chloride polymer,is dissolved out by continuous contact with the HF, hydrocarbon, oralcohol of the system. A small amount of HF from the system dissolves inthe polymerized allyl chloride and the lubricant thereby acquires a highlubricity, as the polymer seems to lose some of its tackiness on contactwith HF.

Allyl chloride is the preferred reactant for the present invention, inview of its high reactivity, relatively low cost, and availability.However, the other allyl halides, particularly the bromide and iodide,may be used, and the resulting products may be preferred for specicapplications. The homologs of the allyl halides, especially Z-methylallyl chloride, are suitable starting materials, but their use is seldomeconomically justified. Various modifications of the invention may bepracticed without departing from the spirit and scope of the appendedclaims.

I claim:

1. A process which comprises subjecting a compound selected from theclass consisting of allyl Substantially above 300 C. to effectsubstantial additional polymerization.

2. A process which comprises subjecting a compound selected from theclass consisting of allyl halides and homologs thereof to oxidativepolymerization, subjecting resulting partially polymerized material topolymerizing reaction with hydrogen fluoride to form afluorine-containing polymer, and heating the last-said polymer at atemperature not substantially above 300 C. to eiect substantialadditional polymerization.

3. The method of preparing a lubricant resistant to the action ofconcentrated hydrouoric acid which comprises subjecting allyl chlorideto reaction with greater than catalytic amounts of concentrated hydrogeniluoride to form a polymer containing combined chlorine and uorine, andheating said polymer at a temperature of 100- 300 C. toA form a viscouspolymer resistant to the action of concentrated hydroiiuoric acid andhaving lubricating properties.

4. 'I'he method of preparing a lubricant resistant to the action ofacids and of hydrocarbons which comprises subjecting allyl chloride topartial polymerization through the action of an oxidizing agent selectedfrom the class consisting of free oxygen and organic peroxides,subjecting the polymer to further polymerization in the presence ofconcentrated hydrogen fluoride to produce a viscous polymer havinglubricating properties and containing combined chlorine and fiuorine butwhich is soluble in concentrated hydrogen fluoride, separating saidviscous polymer from any excess hydrogen uoride, hydrogen chloride, andlow-boiling allyl chloride material, and heating the thus-separatedpolymer at a temperature of 100 C. to 300 C. until the polymer.

becomes substantially insoluble in concentrated hydrogen fluoride.

5. A process which comprises blowing air through a liquid body of freshallyl chloride containing benzoyl peroxide to give a final producthereinafter described which is substantially insoluble inliquidhydrocarbons, distilling on unreacted allyl chloride fromresulting polymer, removing benzoyl peroxide from said polymer,subjecting resulting material yto the action of an excess ofconcentrated hydrogen fluoride to eiect polymerization and reaction withhydrogen iiuoride with accompanying elision of hydrogen chloride,recovering a heavy viscous polymer which contains combined chlorine andfluorine, and heating same at temperatures within the range of 100 to300 C. in the absence of added catalysts to form a iinal productresistant to the action or concentrated hydrogen uoride and havinglubricating properties.

6. A hydrocarbon-resistant and acid-resistantV grease comprising as anessential lubricating constituent thereof a viscous polymeric materialprepared by subjecting allyl chloride rst to the combined action of anorganic peroxide and air to impart hydrocarbon-resistance to the finalpolymeric material, then to reaction with substantially anhydroushydrogen fluoride under conditions eiecting elision of hydrogenchloride, addition of hydrogen fluoride, and polymerization, and then toheating at a temperature of 100 to 300 C. to impart acid-resistance tothe resulting final polymeric material.

'1. As a new composition of matter a tacky viscous polymer of allylchloride, insoluble in concentrated hydrogen fluoride, havinglubricating properties, containing substantial amounts `of combinedchlorine and uorine, and formed by reacting allyl chloride withconcentrated hydrogen uoride followed by heating the resulting polymerat a temperature of to 300 C.

8. A process which comprises subjecting a material selected from thegroup consisting of allyl halides, homologs of allyl halides, andproducts resulting from the partial oxidative polymerization of allylhalides and homologs thereof, to polymerization in the presence ofhydrogen iluoride and then heating the resulting polymer at atemperature not above 300 C. to eilect additional polymerization. U

PAUL H. CARNELL.

REFERENCES crrED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS

